The present invention relates to paper webs and, more particularly, to multi-ply paper webs utilizing recycled paper.
Mounting economic and environmental pressures have led to increased use of recycled paper in the production of paper and paperboard. Reduction of available timberlands have resulted in higher pulpwood prices. Costs associated with compliance with ever increasing air and water cleanup standards have added significant capital costs to paper and paperboard production. Increasing pressures from national, state and local governments and consumer groups to reduce landfill and timber resource usage have all been factors in the increased use of recycled fiber.
However, recycling paper and paperboard has created a new set of technical, operational, economic and environmental problems. Collection and separation of paper and paperboard products is labor intensive, increasing costs. The recycled paper and paperboard must be repulped, cleaned and often de-inked, requiring large quantities of water, chemical usage, and resulting in the need for water treatment. The process is energy intensive due to the need to repulp the wastepaper, pump large quantities of dilute stock, and drain and evaporate large quantities of water. Recycled furnishes cause fouling of stock preparation and papermaking equipment, resulting in increased downtime, further increasing the cost. Continued recycling of the same fibers results in reduction of long fibers, reducing paper strength. Resulting buildups of the shorter fiber and fines reduces drainage on the paper machine, requiring additional drainage equipment and chemical usage. Finally, quality of the recycled paper grades is more difficult to maintain than virgin paper grades. All of the above factors have resulted in increased cost, limiting the use and percentage of recycled fibers in paper and paperboard.
Paper mills, including recycled paper and board mills are capital intensive, partly due to the large amount of equipment required to pump, mix, drain and evaporate the large volumes of water required in the process. This capital intensive aspect has led to large mills widely dispersed, leading to high transportation costs for the furnish used to make the paper as well as transporting of the finished products to the end users.
Alternative processes of recycled paper and paperboard production have sought to answer some of the problems addressed above. Many of these processes incorporate methods to reduce the detrimental effects of using recycled fibers in the production of paper and paperboard. None of the processes significantly addresses better utilization of recycled paper and paperboard.